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Using Masking Fluid (without ruining your paper)

What is Masking Fluid?

Hi world! Today I am going to show you a couple of ways I use masking fluid in my watercolor works. Masking fluid is a removable liquid latex mask with ammonia that resists paint and can be used on unsized papers. It is usually a slightly pigmented off-white that yellows as it dries and is a very sticky, brush destroyer.

I use Winsor & Newton’s ‘Water Colour Art masking Fluid.’

Why Masking Fluid is Amazing

Masking fluid is an incredibly useful material once you learn how to use it. It is perfect for creating clean highlights, avoiding or protecting small areas too delicate to avoid with your brush, and for creating sharp lines and color separations.

It is pretty safe to say that at this point I use masking fluid in all of my watercolor works. I love it. I do not have a very clean or delicate hand, and this medium really helps me create a sharper look in my illustrations.

But Beware, Masking Fluid can be Evil

So the first time I bought masking fluid must have been about five years ago and it took me forever to try it. When I did it ruined everything. I destroyed my brushes, tore my paper, smudged my colors and did not touch the stuff again for months.

So, word for the wise – use cheap brushes intended for destruction. I have two brushes I trim regularly to use only for masking fluid.

Timing is important. The first time I used masking fluid I laid it out then tried to use watercolors right after. The masking fluid HAS to dry first. Let it. Then, I tried to remove the masking fluid when the watercolors and therefore paper was still wet. This tore the paper. Let the PAPER dry. (Are you starting to see my lack of patience kills me?)

Then, I acted like the masking fluid could be treated as paint. I left my work alone to dry with the mask still on and did not return to it for probably a week. Bad idea. If left on too long the mask basically melts partially into the paper and cannot be removed, ever. Sometimes I still make this mistake. Try to avoid working in unbearably hot temperatures as it speeds up this permanent adhesion.

What I Use

Watercolor paper

Watercolor paints

Brushes both for watercolors and the masking fluid


Ruler for the edges (I do not like using tape on my paper)

An eraser


The Steps I Take:

1.Start with your pencil outline. You need to plan ahead with masking fluid so you know where everything goes and in which layers.

2. Don’t shake the masking fluid bottle and pour about a half-tablespoon into a shallow cup. You can work straight from the bottle but I do not like working from such a large container, I prefer to use the cap. If you do use the cap be sure to wipe it out before placing it back on the bottle or it will glue itself shut. Also be sure not to leave the lid off for too long to reduce drying in the bottle.

3. Using a toothpick, sharp edge or your cheap brush, mark your outline edges and any areas you want to remain white or create a clean line with the masking fluid. In this example I have outline my main form because I intend on creating a high color contrast with black and I do not want the paint to spread on the paper.

4. Let dry, dry, dry. (About 20 minutes)

5. Now go ahead and lay down your first watercolor wash and let dry.

6. Repeat as need. You can leave the first layer of masking fluid on until the end or you can take some off, and add more on. You can put the mask on already painted sections but be sure the paper is completely dry and be aware that the mask will lift off a little of the color in the removal process.

7. When you are ready to take of the mask, you can use your finger, eraser, or the dried masking fluid. Be gentle and try not to erase the paper, as it will weaken the page. I like using the dried masking fluid as my eraser as it sticks to itself easily and lifts all the little pieces off the paper in one motion.

I hope you enjoyed this entry and give masking fluid a try sometime; it can be such a fantastic tool once you get past the growing pains.

About Me, Fia Sutton

Hi & welcome to my blog! I am a children's illustrator living in Brooklyn, NY. I create handmade collages, 

watercolors & books that celebrate color, acceptance, & discovery. I am a creator of messy mistakes & happy surprises.

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